使用spring对RMI的支持,可以非常容易地构建你的分布式应用。在服务端,可以通过Spring的org.springframework.remoting.rmi.RmiServiceExporter可以暴露你的服务;在客户端,通过org.springframework.remoting.rmi.RmiProxyFactoryBean可以使用服务端暴露的服务,非常方便。这种C/S模型的访问方式,可以屏蔽掉RMI本身的复杂性,如服务端Skeleton和客户端Stub等的处理细节,这些对于服务开发和服务使用的人员来说,都是透明的,无需过度关注,而集中精力开发你的商业逻辑。
下面通过一个例子,说明如何通过Spring集成RMI。
服务端发布服务
我们定义了服务接口,服务端实现该服务接口来完成其复杂的逻辑,客户端可以通过该接口调用服务端暴露的服务,如下所示:
- package org.shirdrn.spring.remote.rmi;
- public interface AccountService {
- int queryBalance(String mobileNo);
- String shoopingPayment(String mobileNo, byte protocol);
- }
服务实现,示例如下所示:
- package org.shirdrn.spring.remote.rmi;
- import org.apache.log4j.Logger;
- public class MobileAccountServiceImpl implements AccountService {
- private static final Logger LOG = Logger.getLogger(MobileAccountServiceImpl.class);
- public int queryBalance(String mobileNo) {
- if (mobileNo != null)
- return 100;
- return 0;
- }
- public String shoopingPayment(String mobileNo, byte protocol) {
- StringBuffer sb = new StringBuffer().append("Your mobile number is /"").append(
- mobileNo).append("/", protocol type is /"").append(protocol)
- .append("/".");
- LOG.info("Message is: " + sb.toString());
- return sb.toString();
- }
- }
服务端发布服务,供客户端进行(远程方法)调用,Spring配置server.xml如下所示:
- <?xml version="1.0" encoding="UTF-8"?>
- <beans xmlns="http://www.springframework.org/schema/beans"
- xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
- xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
- <bean id="serviceExporter" class="org.springframework.remoting.rmi.RmiServiceExporter">
- <property name="serviceName" value="MobileAccountService" />
- <property name="service" ref="accountService" />
- <property name="serviceInterface"
- value="org.shirdrn.spring.remote.rmi.AccountService" />
- <property name="registryPort" value="8080" />
- <property name="servicePort" value="8088" />
- </bean>
- <bean id="accountService" class="org.shirdrn.spring.remote.rmi.MobileAccountServiceImpl" />
- </beans>
上面配置,指定了暴露的服务的名称,通过serviceName属性注入到RmiServiceExporter中,服务名称为MobileAccountService,客户端通过该服务名称就能够进行调用。
下面启动服务端,发布服务,如下所示:
- package org.shirdrn.spring.remote.rmi;
- import org.springframework.context.support.ClassPathXmlApplicationContext;
- public class RmiServer {
- public static void main(String[] args) throws InterruptedException {
- new ClassPathXmlApplicationContext("org/shirdrn/spring/remote/rmi/server.xml");
- Object lock = new Object();
- synchronized (lock) {
- lock.wait();
- }
- }
- }
客户端调用服务
客户端配置client.xml如下所示:
- <?xml version="1.0" encoding="UTF-8"?>
- <beans xmlns="http://www.springframework.org/schema/beans"
- xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
- xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
- <bean id="mobileAccountService" class="org.springframework.remoting.rmi.RmiProxyFactoryBean">
- <property name="serviceUrl" value="rmi://192.168.1.103:8080/MobileAccountService" />
- <property name="serviceInterface"
- value="org.shirdrn.spring.remote.rmi.AccountService" />
- </bean>
- </beans>
配置中,将一个serviceUrl和serviceInterface注入给RmiProxyFactoryBean,即可进行远程方法调用。调用示例如下所示:
- package org.shirdrn.spring.remote.rmi;
- import org.apache.log4j.Logger;
- import org.springframework.context.ApplicationContext;
- import org.springframework.context.support.ClassPathXmlApplicationContext;
- public class RmiClient {
- private static final Logger LOG = Logger.getLogger(RmiClient.class);
- public static void main(String[] args) {
- ApplicationContext ctx = new ClassPathXmlApplicationContext(
- "org/shirdrn/spring/remote/rmi/client.xml");
- AccountService accountService = (AccountService) ctx
- .getBean("mobileAccountService");
- String result = accountService.shoopingPayment("13800138000", (byte) 5);
- LOG.info(result);
- }
- }
可见,实现远程访问变得非常容易。